drivers/watchdog/rti_wdt.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Watchdog driver for the K3 RTI module
   4  *
   5  * (c) Copyright 2019-2020 Texas Instruments Inc.
   6  * All rights reserved.
   7  */
   8
   9 #include <linux/clk.h>
  10 #include <linux/device.h>
  11 #include <linux/err.h>
  12 #include <linux/io.h>
  13 #include <linux/kernel.h>
  14 #include <linux/mod_devicetable.h>
  15 #include <linux/module.h>
  16 #include <linux/moduleparam.h>
  17 #include <linux/platform_device.h>
  18 #include <linux/pm_runtime.h>
  19 #include <linux/types.h>
  20 #include <linux/watchdog.h>
  21
  22 #define DEFAULT_HEARTBEAT 60
  23
  24 /* Max heartbeat is calculated at 32kHz source clock */
  25 #define MAX_HEARTBEAT   1000
  26
  27 /* Timer register set definition */
  28 #define RTIDWDCTRL      0x90
  29 #define RTIDWDPRLD      0x94
  30 #define RTIWDSTATUS     0x98
  31 #define RTIWDKEY        0x9c
  32 #define RTIDWDCNTR      0xa0
  33 #define RTIWWDRXCTRL    0xa4
  34 #define RTIWWDSIZECTRL  0xa8
  35
  36 #define RTIWWDRX_NMI    0xa
  37
  38 #define RTIWWDSIZE_50P          0x50
  39 #define RTIWWDSIZE_25P          0x500
  40 #define RTIWWDSIZE_12P5         0x5000
  41 #define RTIWWDSIZE_6P25         0x50000
  42 #define RTIWWDSIZE_3P125        0x500000
  43
  44 #define WDENABLE_KEY    0xa98559da
  45
  46 #define WDKEY_SEQ0              0xe51a
  47 #define WDKEY_SEQ1              0xa35c
  48
  49 #define WDT_PRELOAD_SHIFT       13
  50
  51 #define WDT_PRELOAD_MAX         0xfff
  52
  53 #define DWDST                   BIT(1)
  54
  55 static int heartbeat = DEFAULT_HEARTBEAT;
  56
  57 /*
  58  * struct to hold data for each WDT device
  59  * @base - base io address of WD device
  60  * @freq - source clock frequency of WDT
  61  * @wdd  - hold watchdog device as is in WDT core
  62  */
  63 struct rti_wdt_device {
  64         void __iomem            *base;
  65         unsigned long           freq;
  66         struct watchdog_device  wdd;
  67 };
  68
  69 static int rti_wdt_start(struct watchdog_device *wdd)
  70 {
  71         u32 timer_margin;
  72         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
  73
  74         /* set timeout period */
  75         timer_margin = (u64)wdd->timeout * wdt->freq;
  76         timer_margin >>= WDT_PRELOAD_SHIFT;
  77         if (timer_margin > WDT_PRELOAD_MAX)
  78                 timer_margin = WDT_PRELOAD_MAX;
  79         writel_relaxed(timer_margin, wdt->base + RTIDWDPRLD);
  80
  81         /*
  82          * RTI only supports a windowed mode, where the watchdog can only
  83          * be petted during the open window; not too early or not too late.
  84          * The HW configuration options only allow for the open window size
  85          * to be 50% or less than that; we obviouly want to configure the open
  86          * window as large as possible so we select the 50% option.
  87          */
  88         wdd->min_hw_heartbeat_ms = 500 * wdd->timeout;
  89
  90         /* Generate NMI when wdt expires */
  91         writel_relaxed(RTIWWDRX_NMI, wdt->base + RTIWWDRXCTRL);
  92
  93         /* Open window size 50%; this is the largest window size available */
  94         writel_relaxed(RTIWWDSIZE_50P, wdt->base + RTIWWDSIZECTRL);
  95
  96         readl_relaxed(wdt->base + RTIWWDSIZECTRL);
  97
  98         /* enable watchdog */
  99         writel_relaxed(WDENABLE_KEY, wdt->base + RTIDWDCTRL);
 100         return 0;
 101 }
 102
 103 static int rti_wdt_ping(struct watchdog_device *wdd)
 104 {
 105         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 106
 107         /* put watchdog in service state */
 108         writel_relaxed(WDKEY_SEQ0, wdt->base + RTIWDKEY);
 109         /* put watchdog in active state */
 110         writel_relaxed(WDKEY_SEQ1, wdt->base + RTIWDKEY);
 111
 112         return 0;
 113 }
 114
 115 static int rti_wdt_setup_hw_hb(struct watchdog_device *wdd, u32 wsize)
 116 {
 117         /*
 118          * RTI only supports a windowed mode, where the watchdog can only
 119          * be petted during the open window; not too early or not too late.
 120          * The HW configuration options only allow for the open window size
 121          * to be 50% or less than that.
 122          */
 123         switch (wsize) {
 124         case RTIWWDSIZE_50P:
 125                 /* 50% open window => 50% min heartbeat */
 126                 wdd->min_hw_heartbeat_ms = 500 * heartbeat;
 127                 break;
 128
 129         case RTIWWDSIZE_25P:
 130                 /* 25% open window => 75% min heartbeat */
 131                 wdd->min_hw_heartbeat_ms = 750 * heartbeat;
 132                 break;
 133
 134         case RTIWWDSIZE_12P5:
 135                 /* 12.5% open window => 87.5% min heartbeat */
 136                 wdd->min_hw_heartbeat_ms = 875 * heartbeat;
 137                 break;
 138
 139         case RTIWWDSIZE_6P25:
 140                 /* 6.5% open window => 93.5% min heartbeat */
 141                 wdd->min_hw_heartbeat_ms = 935 * heartbeat;
 142                 break;
 143
 144         case RTIWWDSIZE_3P125:
 145                 /* 3.125% open window => 96.9% min heartbeat */
 146                 wdd->min_hw_heartbeat_ms = 969 * heartbeat;
 147                 break;
 148
 149         default:
 150                 return -EINVAL;
 151         }
 152
 153         return 0;
 154 }
 155
 156 static unsigned int rti_wdt_get_timeleft_ms(struct watchdog_device *wdd)
 157 {
 158         u64 timer_counter;
 159         u32 val;
 160         struct rti_wdt_device *wdt = watchdog_get_drvdata(wdd);
 161
 162         /* if timeout has occurred then return 0 */
 163         val = readl_relaxed(wdt->base + RTIWDSTATUS);
 164         if (val & DWDST)
 165                 return 0;
 166
 167         timer_counter = readl_relaxed(wdt->base + RTIDWDCNTR);
 168
 169         timer_counter *= 1000;
 170
 171         do_div(timer_counter, wdt->freq);
 172
 173         return timer_counter;
 174 }
 175
 176 static unsigned int rti_wdt_get_timeleft(struct watchdog_device *wdd)
 177 {
 178         return rti_wdt_get_timeleft_ms(wdd) / 1000;
 179 }
 180
 181 static const struct watchdog_info rti_wdt_info = {
 182         .options = WDIOF_KEEPALIVEPING,
 183         .identity = "K3 RTI Watchdog",
 184 };
 185
 186 static const struct watchdog_ops rti_wdt_ops = {
 187         .owner          = THIS_MODULE,
 188         .start          = rti_wdt_start,
 189         .ping           = rti_wdt_ping,
 190         .get_timeleft   = rti_wdt_get_timeleft,
 191 };
 192
 193 static int rti_wdt_probe(struct platform_device *pdev)
 194 {
 195         int ret = 0;
 196         struct device *dev = &pdev->dev;
 197         struct watchdog_device *wdd;
 198         struct rti_wdt_device *wdt;
 199         struct clk *clk;
 200         u32 last_ping = 0;
 201
 202         wdt = devm_kzalloc(dev, sizeof(*wdt), GFP_KERNEL);
 203         if (!wdt)
 204                 return -ENOMEM;
 205
 206         clk = clk_get(dev, NULL);
 207         if (IS_ERR(clk))
 208                 return dev_err_probe(dev, PTR_ERR(clk), "failed to get clock\n");
 209
 210         wdt->freq = clk_get_rate(clk);
 211
 212         clk_put(clk);
 213
 214         if (!wdt->freq) {
 215                 dev_err(dev, "Failed to get fck rate.\n");
 216                 return -EINVAL;
 217         }
 218
 219         /*
 220          * If watchdog is running at 32k clock, it is not accurate.
 221          * Adjust frequency down in this case so that we don't pet
 222          * the watchdog too often.
 223          */
 224         if (wdt->freq < 32768)
 225                 wdt->freq = wdt->freq * 9 / 10;
 226
 227         pm_runtime_enable(dev);
 228         ret = pm_runtime_get_sync(dev);
 229         if (ret < 0) {
 230                 pm_runtime_put_noidle(dev);
 231                 pm_runtime_disable(&pdev->dev);
 232                 return dev_err_probe(dev, ret, "runtime pm failed\n");
 233         }
 234
 235         platform_set_drvdata(pdev, wdt);
 236
 237         wdd = &wdt->wdd;
 238         wdd->info = &rti_wdt_info;
 239         wdd->ops = &rti_wdt_ops;
 240         wdd->min_timeout = 1;
 241         wdd->max_hw_heartbeat_ms = (WDT_PRELOAD_MAX << WDT_PRELOAD_SHIFT) /
 242                 wdt->freq * 1000;
 243         wdd->parent = dev;
 244
 245         watchdog_set_drvdata(wdd, wdt);
 246         watchdog_set_nowayout(wdd, 1);
 247         watchdog_set_restart_priority(wdd, 128);
 248
 249         wdt->base = devm_platform_ioremap_resource(pdev, 0);
 250         if (IS_ERR(wdt->base)) {
 251                 ret = PTR_ERR(wdt->base);
 252                 goto err_iomap;
 253         }
 254
 255         if (readl(wdt->base + RTIDWDCTRL) == WDENABLE_KEY) {
 256                 int preset_heartbeat;
 257                 u32 time_left_ms;
 258                 u64 heartbeat_ms;
 259                 u32 wsize;
 260
 261                 set_bit(WDOG_HW_RUNNING, &wdd->status);
 262                 time_left_ms = rti_wdt_get_timeleft_ms(wdd);
 263                 heartbeat_ms = readl(wdt->base + RTIDWDPRLD);
 264                 heartbeat_ms <<= WDT_PRELOAD_SHIFT;
 265                 heartbeat_ms *= 1000;
 266                 do_div(heartbeat_ms, wdt->freq);
 267                 preset_heartbeat = heartbeat_ms + 500;
 268                 preset_heartbeat /= 1000;
 269                 if (preset_heartbeat != heartbeat)
 270                         dev_warn(dev, "watchdog already running, ignoring heartbeat config!\n");
 271
 272                 heartbeat = preset_heartbeat;
 273
 274                 wsize = readl(wdt->base + RTIWWDSIZECTRL);
 275                 ret = rti_wdt_setup_hw_hb(wdd, wsize);
 276                 if (ret) {
 277                         dev_err(dev, "bad window size.\n");
 278                         goto err_iomap;
 279                 }
 280
 281                 last_ping = heartbeat_ms - time_left_ms;
 282                 if (time_left_ms > heartbeat_ms) {
 283                         dev_warn(dev, "time_left > heartbeat? Assuming last ping just before now.\n");
 284                         last_ping = 0;
 285                 }
 286         }
 287
 288         watchdog_init_timeout(wdd, heartbeat, dev);
 289
 290         ret = watchdog_register_device(wdd);
 291         if (ret) {
 292                 dev_err(dev, "cannot register watchdog device\n");
 293                 goto err_iomap;
 294         }
 295
 296         if (last_ping)
 297                 watchdog_set_last_hw_keepalive(wdd, last_ping);
 298
 299         return 0;
 300
 301 err_iomap:
 302         pm_runtime_put_sync(&pdev->dev);
 303         pm_runtime_disable(&pdev->dev);
 304
 305         return ret;
 306 }
 307
 308 static int rti_wdt_remove(struct platform_device *pdev)
 309 {
 310         struct rti_wdt_device *wdt = platform_get_drvdata(pdev);
 311
 312         watchdog_unregister_device(&wdt->wdd);
 313         pm_runtime_put(&pdev->dev);
 314         pm_runtime_disable(&pdev->dev);
 315
 316         return 0;
 317 }
 318
 319 static const struct of_device_id rti_wdt_of_match[] = {
 320         { .compatible = "ti,j7-rti-wdt", },
 321         {},
 322 };
 323 MODULE_DEVICE_TABLE(of, rti_wdt_of_match);
 324
 325 static struct platform_driver rti_wdt_driver = {
 326         .driver = {
 327                 .name = "rti-wdt",
 328                 .of_match_table = rti_wdt_of_match,
 329         },
 330         .probe = rti_wdt_probe,
 331         .remove = rti_wdt_remove,
 332 };
 333
 334 module_platform_driver(rti_wdt_driver);
 335
 336 MODULE_AUTHOR("Tero Kristo <t-kristo@ti.com>");
 337 MODULE_DESCRIPTION("K3 RTI Watchdog Driver");
 338
 339 module_param(heartbeat, int, 0);
 340 MODULE_PARM_DESC(heartbeat,
 341                  "Watchdog heartbeat period in seconds from 1 to "
 342                  __MODULE_STRING(MAX_HEARTBEAT) ", default "
 343                  __MODULE_STRING(DEFAULT_HEARTBEAT));
 344
 345 MODULE_LICENSE("GPL");
 346 MODULE_ALIAS("platform:rti-wdt");